Cotton is widely considered as a promising precursor material for aerogels due to its biodegradability, abundance, and non-toxicity. Furthermore, it is a low cost and renewable resource, making it an auspicious material for the addressing of environmental problems. Therefore, numerous studies have reported the utilization of cotton aerogels as superabsorbents for various different applications (e.g. cleaning up of oil spills or water purification).
Based on recent developments, allowing for the production of modified hydrophobic cotton aerogels, researchers from the South China University of Technology Guangzhou have come up with a new ingenious field of application — the trapping of methane bubbles, released by underground sea sediments, from water.

This application is of a special interest as methane is a very potent greenhouse gas, being responsible for approximately one fifth of the atmospheric greenhouse effect. Since aquatic system such as lakes, rivers or oceans are considered to be major sources of methane, releasing trapped gases to the atmosphere via bubbles, the capturing and safe storage of methane bubbles originating from marine environments could mitigate the negative impacts of climate change substantially.

In order to explore this idea, the research team from the South China University of Technology synthesized cotton aerogels (CAs) of varying cotton concentrations via freeze-drying. To ensure the hydrophobicity of the aerogels, the CAs were thereafter silanized with methyltrimethoxysilane, using a thermal chemical vapor deposition method. This resulted in stable monolithic cotton aerogels, which showed promising methane absorption characteristics under both static and dynamic conditions.
By submerging the different hydrophobic cotton aerogels (HCAs) in artificial seawater and exposing them to gaseous methane, it was found that the static absorption capacity increased with decreasing cotton concentration (i.e. larger porosity) and increasing submergence depth. Furthermore, the assessment of the dynamic absorptivity of the samples via compression/recovery cycles revealed that the process exhibits an outstanding repeatability, as the samples retained their absorption capacity to large extents.
With the aim of investigating a continuous strategy to safely transport methane above sea level, a pipe connecting the HCAs to the water surface was attached to the aerogel monoliths. This approach, which is schematically shown in the figure below, led to a steady and controlled transport of methane to the surface, as the bubbles trapped within the aerogel travelled through the pipe due to the existing pressure difference, resulting in an immediate recovery of the aerogel absorption capacity.

Schematic of continuous methane bubble trapping via a HCAs connected to a pipe.

 
Certainly, the reduction of methane emissions from lakes and oceans could have a substantial positive impact on the world-wide greenhouse gas emissions. Therefore, the novel findings motivate a further investigation of the climate change mitigation potential of the deployment of (aerogel-based) methane bubble absorbents in aquatic systems.
The hydrophobic aerogels investigated in this study are not only captivating because of their excellent methane absorptivity, but also exhibit outstanding properties in terms of bio-compatibility and non-toxicity, paving the way for large scale deployment even in fragile eco-systems.
If further positive results in this field can be achieved, the trapping of methane from seawater could even become an economical process, with the captured methane being sold to compensate for the required investment and operational costs.

More details: Nan Li  et al. “A Low-cost, Sustainable and Environmentally Sound Cellulose Absorbent with High Efficiency for Collecting Methane Bubbles from Seawater” ACS Sustainable Chem. Eng. https://pubsdc3.acs.org/doi/pdf/10.1021/acssuschemeng.8b00146

Despite their intriguing characteristics (e.g. ultralow density, high porosity & electrical conductivity), the application of carbon aerogels is generally limited by their poor mechanical strength and brittleness. Researchers from the Zhejiang University (China) were now able to manufacture highly flexible, binary carbon aerogels (bCAs) consisting of graphene and multi-walled carbon nanotubes (MWNTs), which can resist compressive and tensile stresses. These novel bCAs were successfully used as strain sensors to detect complex three dimensional movements.

The novel aerogels were fabricated by creating an aqueous solution equipped of graphene oxide and MWNTs which was then given shape by additive 3D-printing. Thereafter, the structures were freeze-dried before being chemically or thermally reduced.

Owing to their hierarchical assembly, which is schematically shown in the figure below, the novel bCAs exhibit an extraordinary stretching stability over a wide range of conditions (e.g. temperatures from 93-773 K). Furthermore, they exhibit a noteworthy fatigue resistance, being able to retain their structural shape to great extents for at least 100 cycles at 200 % tensile strain.

Schematic of hierarchical assembly of bCAs, stretching from centimeter to nanometer range. Fourth order: Graphene and MWNT molecular blocks; Third order: graphene laminates; Second Order: Polygon cell; First Order: Macroscopic truss structure

Another key characteristic of the bCAs is their change in resistance in tension (gentle increase) and compression (steep increase). Exploiting this feature, the researchers equipped the joints of a snake-like robot with bCAs to be able to sense the robot’s movements and configurations. As shown in the figure below, a sensor array consisting of three bCAs was sufficient to map the continuously changing configurations and hence accurately identify the robot’s movements.

Illustration of working principle of a three bCAs sensor array to identify the movements of a snake-like robot

 
The authors identify other potential applications of the bCAs in wearable electronic devices, lightweight mechanical devices and fields of application requiring robustness and reliability in the most extreme conditions (e.g. aerospace engineering). Furthermore, the researchers are confident that their assembly method can be deployed for the fabrication of other highly stretchable aerogel materials.

More details: Fan Guo et al. “Highly stretchable carbon aerogels.” Nature Communications. https://www.nature.com/articles/s41467-018-03268-y
Read more: https://phys.org/news/2018-03-rubbery-carbon-aerogels-greatly-applications.html

The German chemical company BASF Polyurethanes GmbH has won the German Design Award for its Excellent Product Design in the category Building and Elements. The jury selected the aerogel insulation material SLENTITE® due to its unique combination of properties, facilitating space-saving insulation concepts which open up entirely new creative possibilities to architects and designers.

Award-winning SLENTITE® aerogel material for ultra thin building insulation

The novel aerogel material, consisting of 90 % air, allows for the reduction of insulation thicknesses by 50 %, when compared to standard insulation materials. Besides its outstanding thermal insulation properties, it is the first solid, breathable aerogel panel produced from polyurethane. Furthermore, it is easily machined without excessive dust generation, allowing for tailored shapes & sizes and direct application on walls or facades.

Consequently, the SLENTITE^® thermal insulation panels eclipse any commercial insulation material while fulfilling all demands placed on modern building materials.
Its honoring by the German Design Award jury could spark the interest of potential customers and competitors, stimulating the aerogel insulation material market.

Read more:
http://www.german-design-award.com/en/the-winners/gallery/detail/17074-slentite.html
https://www.basf.com/en/company/news-and-media/news-releases/2018/02/p-18-120.html
https://www.bi-medien.de/artikel-24501-bm-extrem-schlanke-daemmplatte-von-basf.bi

Researchers from the Kyoto University (Japan) successfully synthesized transparent, machinable, scalable, super-compressible, highly elastic and super-insulating polyvinylpolymethylsiloxane aerogels and xerogels. Remarkably, the study reports that these outstanding features were present not only in aerogels produced using supercritical drying, but in those produced using ambient pressure drying, too.

The sample preparation was achieved by mixing vinylmethyldimethoxysilane (VMDMS) or vinylmethyldiethoxysilane (VMDES) with 1-5 % of di-tert-butyl peroxide (DTBP), to initiate the radical polymerization at 120 °C, yielding a transparent viscous liquid mainly containing polyvinylmethyldimethoxysilane (PVMDMS) or polyvinylmethyldiethoxysilane (PVMDES). Thereafter, BzOH, H₂O and tetramethylammonium hydroxide (TMAOH) were added to the liquid and the mixture was heated to 80 °C for one hour to obtain transparent and flexible gels. Prior to solvent exchange with isopropanol (IPA), the gels were aged between four or five days at 80-100 °C. Removal of the liquid was subsequently accomplished in three different ways (see Figure below): (1) supercritical drying with CO₂; (2) solvent exchange into n-hexane followed by drying at ambient pressure; (3) direct drying from IPA at ambient pressure.

Comparison of different drying methods to obtain PVMDMS or PCMDES aerogels and xerogels.

It was established that key to the intriguing properties of the dried aerogels and xerogels are their homogeneous porous nanostructure, composed of flexible hydrocarbon chains chemically cross-linked with polymethylsiloxanes. Notably, this type of nanostructure structure exhibited low densities (0.16-0.22 g/cm³) and heat conductivities (15.0-15.4 mW/m K), as well as high specific surface areas (900-1000 m²/g), good transparency (>80 % light transmittance), and extraordinary flexibility (see attached video). Additionally, the flexible network structures allowed for a recovery of the evaporation-induced gel shrinkage through a “spring-back” effect (see Figure below), making the supercritical drying step dispensable.

Progression of gel volume during ambient pressure drying. “spring-back” effect yields xerogels of nearly the same volume as the parent gel.

In summary, these findings imply that an ultra-low cost pathway to manufacture aerogels by ambient pressure drying while still preserving extraordinary properties required for applications as superinsulators has been established. This means that one of the main obstacles for the broad application of aerogels — their high manufacturing costs — has been overcome, which might pave the way for their large scale deployment.

More details: Zu et al.; Transparent, Superflexible Doubly Cross-Linked Polyvinylpolymethylsiloxane Aerogel Superinsulators via Ambient Pressure Drying , ACS Nano, January 8, 2018. https://doi.org/10.1021/acsnano.7b07117

Video of aerogel bending test: Click Here

The search for active yet economical water purification strategies is in full swing as increasing industrial activity results in sharp surges in wastewater production, and the ever-growing global population increases demand for clean drinking water.

Commonly, separated, sophisticated absorption processes are deployed to remove either organic or inorganic contaminants from sewage water due to their high efficiency and moderate cost. However, it remains a challenge to devise robust, efficient and economical absorbents for the wide range of trace elements occurring in wastewater. Ideally, novel absorption materials should be able to remove inorganic compounds such as dyes or heavy metals and also be active against harmful viral or bacterial pathogens.

In pursuit of such a material, researchers from Jinan University (China) have synthesized an aerogel structure exhibiting extraordinary dye and heavy metal absorbing properties, by using graphene oxide (GO) and a type of abundant mineral called montmorillonite (MMT). The desired anti-pathogenic activity was realized through equipping the aerogel matrix with a common anti-bacterial agent, resulting in absorbents displaying excellent antibacterial activity against Gram-positive and Gram-negative bacteria.

The aerogel material exhibiting these intriguing properties was manufactured through mixing GO powder, ascorbic acid, and a MMT solution, then inducing gelation through heat treatment at 95 °C. After aging of the hydrogel in a PVA solution for two days, the gel was then freeze dried at -55 °C, resulting in a monolithic aerogel structure, which is shown in the Figure below.

Image of black GO-MMT aerogel placed on top of kapok tree fiber.

Absorption experiments showed that the aerogel absorbents were not only able to remove more than 95 % of methyl orange and methylene blue dyes from aqueous solutions, but also exhibited great properties for the removal of heavy metals from water (e.g. >90 % removal efficiency for chromium ion removal). This activity was found to be stable over numerous absorption/desorption cycles, with sample regeneration being achieved by vigorous shaking. Furthermore, the addition of antibacterial dodecyl dimethyl benzyl ammonium chloride (1227) to the initial precursor solution was found to provide the aerogel with antibacterial activity, which was shown using E. coli and S. aureus bacteria cultures, each losing over 90 % of their cell viability in the presence of the GO-MMT-1227 aerogel material.

Due to these extraordinary findings, the researchers are confident that they have found an efficient, versatile, recyclable, and robust absorbent material, which has the potential to revolutionize water purification. If economical large scale manufacturing and long term stability can be achieved, the novel material might indeed replace state-of-the-art sorbents in wastewater treatment systems.

More details: Yunyun Zhang et al.; The utilization of a three-dimensional reduced graphene oxide and montmorillonite composite aerogel as a multifunctional agent for wastewater treatment, RSC Adv., 2018,8, 4239-4248. https://doi.org/10.1039/C7RA13103H

Annually, the Swiss Federal Office of Energy awards the Watt d’Or Award to people, companies and organizations that “develop the energy technologies for the future, bring innovative products onto the market and set new standards for practical solutions that unite energy and environment awareness with comfort requirements, aesthetics and economic interests”.
This year, a prototypical aerogel-insulated apartment building, devised by the Zurich-based architectural office Dietrich Schwarz has been awarded the Watt d’Or in the category Buildings and Space.

With new challenges in terms of energy efficiency and space requirements arising, architects are faced with a fundamental conflict — providing highly effective insulation at constant or even slimmer wall thicknesses. The only escape from this dilemma are advancements in insulation materials, yielding scalable structures of extremely low thermal conductivity.
Aerogels are one type of material promising exactly those required characteristics and therefore are generally considered to possess great merit for the future building insulation market.

Award-winning six-floor apartment building concept by the architectural office Dietrich Schwarz, located in Hohlstrasse 100, Zurich (Switzerland)

Due to these intriguing insulating properties of aerogels, the architects of Dietrich Schwarz (Switzerland) have selected aerogel-equipped wood elements to insulate the exterior facade of their latest award-winning project in Zurich (see image above). Thereby, the building floor space was maximized without jeopardizing energetic requirements placed on modern architecture. Additionally, vacuum-insulated windows, phase-change materials in the facades reducing the required cooling and heating demands, rooftop PV panels and a thermal heat pump complete the holistic approach to reduce the energy intensity of modern housing.
Another eye-catching, futuristic feature of the apartment block are its convex oriels, providing sound insulation from the noisy street. Through these elements regular room ventilation via opened windows can be achieved without experiencing excessive noise pollution.

In light of the abundance of novel architectural elements, providing a high level of comfort at vastly reduced energetic footprint, found in this building concept, the selection of the jury of the Swiss Federal Office of Energy does not come as a surprise.
If building concepts such as the one by Dietrich Schwarz will prove their worth, it will only be a matter of time until aerogel-based insulation materials will become a market standard.

Read more at:
https://www.tagesanzeiger.ch/zuerich/stadt/zuercher-architekten-ueberzeugen-mit-ultraduenner-daemmung/story/21704599
https://www.baublatt.ch/verschiedenes/watt-dor-2018-ein-intelligentes-licht-fuer-tier-und-mensch

Announcing the Fourth International Seminar on AEROGELS-2018.

Click here for further details.

The Hamburg based startup Aerogelex has received the ETPN (European Technology Platform for Nanomedicine) Award 2017 for Best Nanomedicine Product/Deal at the Bio-Europe 2017. The awards committee was impressed by Aerogelex’s biopolymer aerogels for wound dressing, pharmaceutical, and life science applications.

Best Nanomedicine Product/Deal 2017 Awardee Aerogelex founder
Dr. Raman Subrahmanyam, Best Nanomedicine Early Clinical Stage Project
Awardee Dr. Su Metcalfe, and ETPN Chairman Patrick Boisseau

Aerogelex’s goal is to facilitate the implementation of aerogels in cosmetic, food, pharmaceutical, and thermal applications by transferring their wealth of knowledge about aerogels and aerogel manufacturing to partners who see value in the performance aerogels can offer.  Aerogelex will partner with companies and research groups to solve the materials and processing challenges associated with bringing aerogels and aerogel-based materials to market.

Aerogelex is currently open to partnership with individuals and companies who looking to establish a foothold in biopolymer aerogels, or who are interested in using supercritical drying in their manufacturing process. Businesses that partner with Aerogelex will get access to an aerogel production plant where aerogel prototypes can be manufactured and optimized. After a successful pilot phase, partnering companies will learn how to manufacture aerogels on a large scale in order to establish their own expertise.

To get a glimpse of the technological opportunities that supercritical drying and biopolymer aerogels offer, curious minds can purchase the first official product from Aerogelex on BuyAerogel.com. The ”AeroEggs” up for sale are unique aerogels made from hard-boiled eggs that reveal the endless possibilities that aerogels can offer.

Full video of Nanomedicine Award ceremony with presentation from Aerogelex founder Dr. Raman Subrahmanyam:  https://www.youtube.com/watch?v=P6JXJBrQVfY&list=PLjyB2R13BJCv4XVHoxm1TsZL_VkZiELDk